Asiana Airlines plans to improve training for its pilots, the carrier’s chief executive said Tuesday, as the investigation into the cause of Saturday’s crash in San Francisco continued.

Asiana chief executive Yoon Young-doo has refused to blame pilot error for the crash, saying, "The two pilots on the plane have enough qualifications, having flown to San Francisco 33 times and 29 times respectively.''

He added, however, that Asiana planned to "beef up" simulated training, especially for non-precision airport approach, referring to a visual landing, as was used by the flight on Saturday. Yoon is due to arrive in San Francisco this morning.

Two passengers on Flight 214 were killed and 180 were injured after the Boeing 777 crash landed at 11:27 a.m. PT.

Investigators from the U.S. and South Korea spoke to the pilot at the controls, Lee Kang-kuk, and another pilot on Monday, Choi Jeong-ho, a senior official for South Korea's Ministry of Land, Infrastructure and Transport, told reporters Tuesday.

On Monday, Deborah Hersman, head of the National Transportation Safety Board, said that the plane was traveling at about 154 mph -- just below its target speed for landing -- when it was still about 500 feet up in the air, according to the flight data recorder.

She said the throttles began to move forward eight seconds prior to impact when the plane was traveling at about 129 mph. Three seconds before impact, the engines were at 50 percent power and gaining power, and traveling at about 118.5 mph. The air speed at impact was about 122 mph.

Hersman stressed the information on the recorder still needed to be validated and cross-checked with other information.

Lee Kang-kuk was undergoing training for 777s but was an experienced pilot with almost 10,000 hours’ flying time. His supervisor was making his first flight as a trainer.

Choi, the South Korean official, said investigators planned to talk to two other pilots on the flight and air controllers on Tuesday.

Landing is part of the training program and it is common practice for pilots in training to land under supervision as part of the type certification process.

Jung Yun-sick, a former Asiana pilot and now a professor at Jungwon University, told Reuters that any new measures were unlikely to increase the number of training hours for pilots trying to shift to a new aircraft.

"The requirement used to be 60 flights of a total of 100 hours some 15 years ago when I was with Asiana," he said, the same as it is now. "It was quite intensive at the time as they didn't have much data on what is really appropriate level of training. But now they have enough data for this and the current level is what is generally accepted globally."

Former NTSB managing director Peter Goelz told The Associated Press that there was a possibility a license could be revoked, or fines or penalties issued.

"The FAA will take a look at this going down the road and see if there were any egregious violations," he said.

As for the interviews, "The reality is this is not going to be an interrogation," he said.

"The NTSB will ask them to tell us in your own words what was going on. The investigators will have some advantage, they'll have some information from voice recorder. But it's not a cross examination, it's an effort to understand what the pilot remembers and what he remembers saying and doing,” Goelz said.

"I think this accident is going to go down as a textbook case study on what they call Cockpit Resource Managements, which is a fancy way of saying how the pilots talk to each other and identify solutions,"

He said it was very helpful, and not all that common after a major crash, to have pilots to interview. "It's always good to have survivors," he said.

South Korea officials said 39 people remained hospitalized in seven different hospitals in San Francisco.

The flight originated in Shanghai, China, and stopped over in Seoul, South Korea, before making the nearly 11-hour trip to San Francisco.

The two teenagers who died, Wang Linjia and Ye Mengyuan, were Chinese girls on their way to a Christian summer camp in the United States. Authorities are investigating whether a fire truck ran over one of them as it raced to help.

The father of Ye Mengyuan, who identified himself only as Mr. Ye, confronted Yoon at Incheon Airport in Seoul in a moment caught on camera by Reuters.

“I am very dissatisfied (with Asiana's efforts). We're meeting with this sort of problems at the very start, very dissatisfied,” Ye’s father told Yoon.

“I offer an apology to families shocked by the sudden accident,” Yoon replied. Yoon shook hands with him and patted his back during the exchange.